feat: add SEO utility functions smartTruncate and buildBreadcrumbList (Task 1)

lib/utils/__tests__/seo.test.ts

@@ -0,0 +1,53 @@
+import { describe, it, expect } from "vitest"
+import { smartTruncate, buildBreadcrumbList, BreadcrumbSegment } from "@/lib/utils/seo"
+
+describe("smartTruncate", () => {
+  it("returns full text when shorter than maxLen", () => {
+    expect(smartTruncate("Short text", 100)).toBe("Short text")
+  })
+
+  it("truncates at word boundary and appends ellipsis", () => {
+    const result = smartTruncate("This is a longer sentence that should be truncated properly.", 30)
+    expect(result).toBe("This is a longer sentence...")
+    expect(result.length).toBeLessThanOrEqual(30 + 3) // + "..."
+  })
+
+  it("handles text with no spaces gracefully", () => {
+    const result = smartTruncate("SuperLongWordThatHasNoSpaces", 10)
+    expect(result).toBe("SuperLongW...")
+  })
+
+  it("does not append ellipsis when text fits exactly", () => {
+    expect(smartTruncate("abc", 3)).toBe("abc")
+  })
+
+  it("handles empty string", () => {
+    expect(smartTruncate("", 10)).toBe("")
+  })
+})
+
+describe("buildBreadcrumbList", () => {
+  it("builds a valid BreadcrumbList from segments", () => {
+    const segments = [
+      { name: "Home", url: "https://deckyvault.xyz" },
+      { name: "Games", url: "https://deckyvault.xyz/games" },
+      { name: "Elden Ring", url: "https://deckyvault.xyz/game/123" },
+    ]
+    const result = buildBreadcrumbList(segments)
+    expect(result["@context"]).toBe("https://schema.org")
+    expect(result["@type"]).toBe("BreadcrumbList")
+    expect(result.itemListElement).toHaveLength(3)
+    expect(result.itemListElement[0]).toEqual({
+      "@type": "ListItem",
+      position: 1,
+      name: "Home",
+      item: "https://deckyvault.xyz",
+    })
+  })
+
+  it("handles a single segment", () => {
+    const segments = [{ name: "Home", url: "https://deckyvault.xyz" }]
+    const result = buildBreadcrumbList(segments)
+    expect(result.itemListElement).toHaveLength(1)
+  })
+})